Electric drink mixers have been used for many years in homes and commercial establishments for mixing a variety of beverages. In recent years, such mixers have become less desirable for commercial use due to stringent sanitation codes. The conventional mixer generally includes a base from which rises a substantially vertical standard, and an electric drive motor projects over the base from the top of the standard. The motor carries a depending stirring arm which extends into a container supported by suitable support hardware attached to the front of the standard. The front face of the standard is also generally provided with openings for projecting switch operators which control the electrical drive circuitry mounted internally within the standard.
During the operation of an electric drink mixer, the stirring arm rotates at high speeds resulting in some splattering of the stirred liquid, particularly if the liquid container is overfilled. Also, once a drink is mixed, mixer operators have the tendency to remove the drink container before rotation of the stirring arm ceases. This causes the stirring arm to throw liquid against the face of the standard.
In the past, the contamination problem experienced by electric drink mixers as a result of liquid splatter has been recognized. For example, splash guards of the type illustrated by U.S. Pat. No. 2,134,261 to B. M. Oswell have been developed to prevent liquid from splashing onto a wall behind a drink mixer. These splash guards are attached behind the mixer standard, and although they operate effectively to protect objects external to the mixer, they do not protect the mixer standard and hardware on the standard face from contamination.
Electric circuitry for electric drink mixers has been placed in a hollow standard in an attempt to protect such circuitry from contamination, and sliding switches have been developed with operators which project through openings in the front face of the mixer standard. Constructions of this type, illustrated by U.S. Pat. Nos. 1,729,966 to P. H. Robinson et al., 1,764,337 to E. Bielsen and 2,585,822 to L. Meyers did provide limited splash protection to the control circuitry, but the face of the standard, the container mounting and switch hardware, and the drive motor were fully exposed to contamination.
Greatly enhanced splatter protection was provided by the drink mixer construction illustrated by U.S. Pat. No. 3,379,416 to C. L. Smader et al. In this construction, the electronic circuitry for the drink mixer is encased in a hollow standard or column and a switch mechanism is mounted upon the rear wall of the column to avoid contamination entering through the openings in the front face of the column. This switch mechanism includes a spring biased, sliding switch plate having a raised switch contacting surface intermediate the ends of the plate which moves in front and in the plane of a button switch operator. The switch is operated by hardware on the face of the column which is readily removable for cleaning. Also, the drive motor for the mixer is partially encased in a housing so that only the motor hub is subjected to liquid splatter.
Even improved drink mixer constructions of the type illustrated by the Smader et al patent have proven difficult to maintain in a contamination free condition sufficient to meet commercial sanitation standards. The projecting motor hub must be formed of stainless steel or highly machined metal to provide a smooth surface which may be cleaned to remove splattered liquid. The large diameter of the hub projecting through a protective housing creates an annular crack around the hub where liquid contamination builds up. Also, liquid splattered from the stirring arm enters the openings and crevices in the front of the standard where the standard sidewalls mate with the standard front wall and creates contamination which is difficult to eliminate. When splattered material reaches the mixer switch mechanism, the resultant accumulation of sticky material can cause sticking of the switch button as well as inhibiting the free movement of the sliding switch operating mechanism.
It is a primary object of the present invention to provide a novel and improved electric drink mixer having a standard formed with unitary front and sidewalls adjacent the rotary stirrer to provide no crevices for splattered material to enter. These unitary surfaces are easily cleaned after the mixer is used.
Another aspect of the present invention is to provide a novel and improved electric drink mixer wherein the mixer motor including the motor hub is completely enclosed within a housing formed at the top of the standard. The portions of the motor housing adjacent the stirrer arm are formed as a unitary unit with the front and sidewalls of the standard to facilitate cleaning and preclude contamination. The bottom wall of the housing is provided with a single, small opening to receive the stirrer shaft, and this opening is easily closed by a collar formed on the shaft. Since the motor hub is completely enclosed, there is no need to form this hub of stainless steel or other expensive materials which can be readily cleaned.
A further aspect of the present invention is to provide an electric drink mixer having a removable splatter shield mounted to cover the front of the standard and the top of the standard base. This splatter shield is formed of stainless steel or other material which may easily be cleaned and is secured to the standard by a removable switch operator and container support. Vibration preventive mounts are provided on the standard to engage the splatter shield and preclude vibration during operation of the mixer.
Another object of the present invention is to provide an electric drink mixer having a switch assembly including a microswitch which opens the power circuit to the mixer motor when the switch button is depressed. A sliding switch operator is provided to positively depress the switch button and open the power circuit each time the mixer is deactivated, and any sticking of the switch button in the closed position will insure that the power circuit remains open. The sliding switch actuator is a flat plate having no raised surfaces which can contact the biasing spring for the plate and thereby inhibit free plate movement.